Well My mom had 2 kids much younger than me and one was back sleeping and one was tummy sleeping, my mom always worried about it and such but after they were a little older she realized they both slept better on their tummies. So when I had my kids I just followed their lead if they wern't sleeping well on their back I would flip them over and see if tummy sleeping helped and 9 times out of 10 it did. I say you do what works for you. Even more so if you are co sleeping.